What do we mean by Allen’s rule?

Question

Accepted Answer

### Explanation

- Allen's rule states that endothermic animals (mammals and birds) from colder climates tend to have shorter extremities (ears, limbs, tails) to minimize heat loss. This is exactly what statement (1) says, so (1) is correct.

- Statement (2) is unrelated: desert lizards possess physiological and behavioral adaptations (e.g., specialized water conservation, thermoregulation) to cope with high temperatures; this is not Allen's rule.

- Statement (3) describes a xerophytic plant adaptation (leaves reduced to spines and stems taking over photosynthesis), not Allen's rule.

- Statement (4) describes acclimatization/adaptation to hypoxia (high altitude): increased RBC production, altered hemoglobin-oxygen affinity, and increased ventilation—again not Allen's rule.

Only statement (1) matches Allen's rule, so the correct choice is (a).

FINAL_ANSWER: a

Answer

Answer

Answer